Illustration 1 | g00284517 |
Electronic Control System |
Various sensors feed engine data to the electronic control module (ECM). The ECM processes this data. The ECM sends electronic signals to the unit injector solenoids. The solenoids are energized in order to start the fuel discharge from the unit injectors. The solenoids are de-energized in order to stop the fuel discharge from the unit injectors. Refer to Systems Operation, "Electronic Unit Injector" for a complete explanation of the fuel injection process.
The engine incorporates a CAT data link. The data link is used to communicate with other devices that are based on a microprocessor.
The CAT data link can reduce the duplication of sensors within the system by allowing controls to share information. The CAT data link is used to communicate information about the engine to other electronic control systems. The CAT data link is also used to interface with the electronic service tool.
The information about the engine or the machine that is monitored and available on the CAT data link includes the following items.
- Air Filter Restriction
- Atmospheric Pressure
- Cold Mode Status
- Coolant Flow
- Coolant Temperature
- Crankcase Pressure
- Cylinder Output
- Diagnostic Enable Switch Status
- Diagnostic Messages
- ECM Supply Voltage
- Elevated Low Idle Enable Status
- Very Low Engine Oil Level
- Engine Identification
- Engine Speed (Actual rpm)
- Engine Speed (Desired rpm)
- Engine Systems Status
- Engine Warning Status
- Exhaust Temperature To Turbocharger
- FRC Fuel Limit
- Fuel Filter Restriction
- Fuel Position
- Gear Status
- Ground Level Shutdown Switch Status
- High Coolant Temperature Status
- Low Oil Pressure Status
- Machine Speed
- Maximum Air Filter Restriction
- Filtered Oil Pressure
- On Signal Status
- Percent Throttle Position
- Rated Fuel Limit
- Throttle Backup/Diagnostic Enable Switch Status
- Timing Cal Enable/Status
- Total Fuel Consumption
- Turbocharger Inlet Pressure
- Turbocharger Outlet Pressure
An electronic service tool can be used to program the system configuration parameters. These parameters include the following information: the engine serial number, the machine identification, the Full Load Setting (FLS) and the Fuel Ratio Control (FRC) Offset.
When you are trying to set a parameter that requires a factory level security password, the electronic service tool will display a "Factory Password" screen. The password entry screen will display the ECM Serial Number, the Engine Serial Number, the electronic service tool Serial Number, and the total tattletales. In order to acquire these passwords, this information must be shown to an authorized Caterpillar dealer. Factory passwords are controlled by Caterpillar, Inc. The factory passwords may be obtained by authorized Caterpillar dealers.
Note: The passwords are only good for one clearing session. A different set of passwords will be needed after exiting the Display/Change Parameters screen of the electronic service tool.
The tool plugs into the connector for the data link in order to communicate with the ECM. The 7X-1700 Communication Adapter is installed in series between the electronic service tool and the CAT data link connector. The communication adapter converts data that is in the language from the data link. This language is converted to a language that is used by the electronic service tool. The data link connector is located on the rear wall of the cab behind the operator's seat. The electronic service tool can also be used to display the values of all the information for diagnosing engine problems that is available on the data link in real time.
Changes in the programming that are made to the system configuration parameters are logged in the permanent memory of the ECM in order to maintain an audit of unauthorized changes. The system configuration parameters are used to customize the ECM.
Reprogramming the ECM to operate on a different application requires a different personality module and iron changes to the engine. A Caterpillar dealer should be consulted for details.
Air Filter Restriction Indication
The engine's electronic control system determines air filter restriction by calculating the pressure drop across the air filters. The calculation is performed by subtracting air pressure in the air inlet piping from atmospheric pressure. Pressures at both locations are measured by the engine's electronic control system. The maximum air inlet restriction that is recommended is
The ECM latches the maximum air filter restriction value which has been sensed since the ECM has been powered. Any derating will be latched into the engine control system until the ECM is powered down. This action will happen even though the engine may experience excessive air filter restriction only during certain operating conditions that are based on the power demand.
The ECM will start the maximum air filter restriction derating of 20 percent if an incorrect signal from the atmospheric pressure sensor or a turbocharger inlet pressure sensor is sensed by the ECM. This will continue until the problem has been corrected.
The life of the filter will vary depending on the operating environment of the engine.
The ECM on the engine uses the oil level switch in the oil pan. The ECM on the engine provides a signal via the CAT data link to the machine's monitoring panel in order to indicate whether the engine oil level is at an acceptable level. The monitoring panel will warn the operator of an unacceptable engine oil level. An event will be logged in the ECM. The event can be viewed with the electronic service tool. The event can also be cleared with the electronic service tool.
The engine's ECM uses the higher exhaust temperature to the turbocharger in order to provide a signal via the CAT data link to the machine's monitoring panel. The signal will indicate whether the exhaust temperature to the turbocharger is at an acceptable level. The monitoring panel warns the operator of an unacceptable exhaust temperature to the turbocharger. An event will also be logged in the ECM. The event can be viewed with the electronic service tool. A factory password is required in order to clear this event with the electronic service tool.
The ECM will also derate the engine by two percent if the exhaust temperature is above the acceptable level for 60 seconds. The exhaust temperature to the turbocharger must be below the acceptable level after an additional 60 seconds or the engine will be derated another two percent. Derating will continue in steps of two percent. Each step will last for 60 seconds. The steps will continue until the exhaust temperatures go below the acceptable level or the maximum derating of 20 percent is reached. The last level of derating will remain active until the ECM is powered down.
The ECM gets data from the crankcase pressure sensor that is mounted on the camshaft cover. The sensor provides a signal via the CAT data link. The signal goes to the machine's monitoring panel. This will indicate when the engine's crankcase pressure is at an acceptable level. The monitoring panel will warn the operator of an unacceptable crankcase pressure. An event will also be logged in the ECM. The event can be viewed with the electronic service tool. The event can also be cleared with the electronic service tool.
The ECM uses the coolant flow switch at the outlet of the jacket water pump to provide a signal via the CAT data link. The signal goes to the monitoring panel. This signal will indicate when the flow of the jacket water coolant is at an acceptable level. The monitoring panel will warn the operator of unacceptable coolant flow. An event will also be logged in the ECM. The event can be viewed with the electronic service tool. A factory password is required to clear the event with the electronic service tool.
The engine's ECM has a fuel filter differential pressure switch. The switch is mounted in the fuel filter housing. The switch is used to provide a signal via the CAT data link. The signal goes to the monitoring panel. This will indicate when the engine fuel filter restriction is at an acceptable level. The monitoring panel will turn on the service engine lamp in order to warn the operator when the engine fuel filter restriction reaches an unacceptable level. An event will also be logged in the ECM. The event can be viewed with the electronic service tool. The event can also be cleared with the electronic service tool.
Automatic Altitude Compensation
The ECM automatically compensates for engine operation at higher elevations. The electronic control system derates the fuel delivery. The fuel delivery is a function of barometric pressure. The barometric pressure is sensed by the system's atmospheric pressure sensor. The barometric pressure is sensed at a rate of 1 percent per kPa to a maximum rate of 24 percent derating. The maximum derating of the fuel delivery maintains the exhaust temperatures within acceptable limits over a full range of altitudes. Derating by the ECM begins at a specific elevation. The rate of derating is based upon atmospheric pressure. The elevation for beginning derating can be found in the TMI (Technical Marketing Information).
Illustration 2 | g00342672 |
If the ECM senses an incorrect signal from the atmospheric pressure sensor and the turbocharger inlet pressure sensors, the electronic control system will impose the maximum derating for the altitude. The maximum derating for the altitude will be imposed until the problem is corrected.
3508B System Diagnostic Codes | ||
CID(1) | FMI(2) | Description(3) |
1 | 05 | Cylinder 1 Open Circuit |
1 | 06 | Cylinder 1 Short |
2 | 05 | Cylinder 2 Open Circuit |
2 | 06 | Cylinder 2 Short |
3 | 05 | Cylinder 3 Open Circuit |
3 | 06 | Cylinder Short |
4 | 05 | Cylinder 4 Open Circuit |
4 | 06 | Cylinder 4 Short |
5 | 05 | Cylinder 5 Open Circuit |
5 | 06 | Cylinder 5 Short |
6 | 05 | Cylinder 6 Open Circuit |
6 | 06 | Cylinder 6 Short |
7 | 05 | Cylinder 7 Open Circuit |
7 | 06 | Cylinder 7 Short |
8 | 05 | Cylinder 8 Open Circuit |
8 | 06 | Cylinder 8 Short |
91 | 00 | Throttle Switch Not Released |
100 | 03 | Oil Press Open/Short To Batt+ |
100 | 04 | Oil Press Short To Ground |
100 | 13 | Oil Press Calibration Required |
101 | 03 | Crankcase Air Press Open/Short To Batt+ |
101 | 04 | Crankcase Air Press Short To Ground |
101 | 13 | Crankcase Air Press Calibration Required |
110 | 03 | Coolant Temp Open/Short To Batt+ |
110 | 04 | Coolant Temp Short To Ground |
168 | 00 | Battery Voltage Above Normal |
168 | 01 | Battery Voltage Below Normal |
168 | 02 | Battery Voltage Intermittent |
190 | 02 | Loss Of Engine RPM Signal |
190 | 03 | Engine Speed Open/Short To Batt+ |
190 | 08 | Engine Speed Signal Abnormal |
253 | 02 | Personality Module Mismatch |
254 | 12 | Electronic Control Mod |
261 | 13 | Timing Calibration Required |
262 | 03 | Analog Sensor Supply Short To Batt+ |
262 | 04 | Analog Sensor Supply Short To Ground |
263 | 03 | Digital Sensor Supply Short To Batt+ |
263 | 04 | Digital Sensor Supply Short To Ground |
267 | 02 | Shutdown Inputs Are Incorrect |
268 | 02 | Check Programmable Parameters |
273 | 00 | Turbo Out Press Above Normal |
273 | 03 | Turbo Out Press Open/Short To Batt+ |
273 | 04 | Turbo Out Press Short To Ground |
273 | 13 | Turbo Out Press Calibration Required |
274 | 03 | Atmos Press Open/Short To Batt+ |
274 | 04 | Atmos Press Short To Ground |
274 | 13 | Atmospheric Press Calibration Required |
275 | 03 | Turbo In Rt Press Open/Short To Batt+ |
275 | 04 | Turbo In Rt Press Short To Ground |
275 | 13 | Turbo In Rt Press Calibration Required |
276 | 03 | Turbo In Lf Press Open/Short To Ground |
276 | 04 | Turbo In Lf Press Short To Ground |
276 | 13 | Turbo In Lf Press Calibration Required |
277 | 08 | Timing Calibration Signal Abnormal |
290 | 03 | Engine Fan Pump Press Open/Short To Batt+ |
290 | 04 | Engine Fan Pump Press Short To Ground |
291 | 05 | Engine Fan Solenoid Open Circuit |
291 | 06 | Engine Fan Solenoid Short to Ground |
296 | 09 | Unable To Communicate With Transmission |
298 | 02 | Incorrect Serv Brake Pedal Sw Inputs |
545 | 05 | Ether Start Relay Open/Short To Ground |
545 | 06 | Ether Start Relay Short To Ground |
546 | 05 | Ether Hold Relay Open/Short To Ground |
546 | 06 | Ether Hold Relay Short To Batt+ |
548 | 05 | Throttle Lock Lamp Open Circuit |
548 | 06 | Throttle Lock Lamp Short To Ground |
799 | 12 | Need Service Tool Update |
800 | 09 | Unable To Communicate With VIDS |
827 | 08 | Lf Exhaust Temp Signal Abnormal |
828 | 08 | Rt Exhaust Temp Signal Abnormal |
(1) | The Component Identifier is a code which is assigned to each component. |
(2) | The Failure Mode Identifier is a failure of a component. |
(3) | Refer to the Troubleshooting Section for a complete explanation of the diagnostic fault codes. |
3508B System Event Codes | |
EID | Description |
17 | High Engine Coolant Temp Warning |
35 | Loss Of Coolant Flow Warning |
94 | Axle Protection |
100 | Low Engine Oil Press Warning |
101 | High Crankcase Press Warning |
173 | High Exhaust Temp Warning |
190 | Engine Overspeed Warning |
265 | User Defined Shutdown |
272 | Inlet Air Restriction Warning |